In Galbraith's superb fifth novel featuring London PI Cormoran Strike and Robin Ellacott (after 2018's Lethal White), his two leads land a cold case while dealing with major personal problems: the aunt who raised Strike is dying of cancer, and Robin is going through a painful divorce. In 1974, GP Margot Bamborough walked out of her London practice to meet a friend, and was never seen again. The case was originally assigned to Det. Insp. Bill Talbot, who believed Bamborough fell victim to a serial killer, Dennis Creed, but Talbot suffered a mental breakdown while pursuing that theory. Creed, who was arrested in 1976 after a failed abduction attempt, refused to say whether he snatched Bamborough. Almost four decades later, the doctor's daughter, who was one at the time of her mother's disappearance, persuades Strike to try to solve the mystery. As Strike and Robin follow up the slimmest leads and seek to trace any living witnesses, Galbraith (the pseudonym of J.K. Rowling) never loses sight of the tragedy at the heart of the assignment. The painstaking, prosaic investigative work keeps the reader engaged for the duration of this doorstopper. Galbraith will surely have lost some fans due to a controversy that preceded the book's publication, with critics calling the novel transphobic because Creed had dressed as a woman while committing some of his crimes. Those still in the author's camp, though, will likely consider this to be the best series entry to date. Agent: Neil Blair, the Blair Partnership (U.K.). (Sept.)